editorial IUCrJ Crystallography is more than crystal structures ISSN 2052-2525 Sine Larsen* NEUTRONjSYNCHROTRON Department of Chemistry, University of Copenhagen, Universitetsparken 5, Copenhagen, 2100, Denmark. *Correspon- dence e-mail: [email protected]

The triennial IUCr congresses have always been highlights and sources of scientific inspiration in my years as a crystallographer, because not only do they provide the latest results in your own field of interest but they also give an overview of developments of crystallography in all its facets. The 23rd IUCr Congress in Montreal was no exception,

Keywords: crystallography; editorial; neutrons; and it was particularly festive as it was held in the International Year of Crystallography. synchrotron radiation. New research results based on experiments performed with neutrons and synchrotron radiation have always constituted an important component of the Congress. The use of neutrons and synchrotron radiation has increased over the years not only as measured by the number of experiments performed but also by the number of different experimental techniques that are employed. The large research infrastructures are ideal places for crystallographic experiments – not only do they provide neutrons and X-rays but also the technical expertise that enables complex experiments with a variety of techniques. The papers submitted to IUCrJ for the neutron and synchrotron science and tech- nology section reflect the scientific developments observed at IUCr Congresses. A new X-ray technique, rotational X-ray tracking (RXT), has been developed by Liang et al. (2014). They used this technique to study the temperature dependence of a colloidal gel formed by small crystalline alumina particles in decanoic acid, and demonstrated the applicability of RXT for investigation of the viscoelastic properties of Newtonian, and non-Newtonian liquids, solids and their phase transitions. The number of experiments using advanced grazing-incidence techniques for the analysis of soft-matter materials has grown hugely in recent years, owing to progress in instrumentation and data analysis. The IUCrJ feature article by Hexemer & Mu¨ller- Buschbaum (2015), Advanced grazing-incidence techniques for modern soft-matter analysis, is therefore timely. In this review the authors describe how advanced grazing- incidence small- and wide-angle X-ray and neutron scattering (GISAXS, GIWAXS, GISANS and GIWANS) can be used to investigate the morphology of soft-matter materials, the overview being illustrated by excellent examples. Method developments have made it possible to characterize complex soft-matter samples in-depth morpholo- gically. The use of focused micro- to nanometer-sized X-ray beams for the GISAXS and GIWAXS experiments has opened up the study of smaller samples as well as samples in a complex sample environment, like GISAXS with a microfluidic cell. Furthermore, a smaller beam enables very local scattering experiments, which makes it feasible to perform structure determinations of inhomogenous samples. Small-angle X-ray and neutron scattering (SAXS and SANS) methods have also attained great popularity in the crystallographic community for studies of all types of materials. A growing research area is protein solution SAXS, which is a source of structural information for proteins that are difficult to crystallize. In another feature article, Beyond simple small-angle X-ray scattering: developments in online techniques and sample environments by Bras, Koizumi & Terrill (2014), an overview is given of the development of experimental facilities for SAXS experiments at synchrotron radiation facilities. Dedicated SAXS/WAXS (wide-angle X-ray scattering) beamlines are present at most synchrotron radiation facilities and the use of the complementary information available from simultaneous measurement of SAXS and WAXS in time-resolved studies is described well. SAXS and WAXS measurements become even more powerful if they are supported by other types of measurements, and a thorough description of technique combinations and sample environments is also given in the paper by Bras et al. (2014). The advances in SAXS are also shown in other sections of IUCrJ, as illustrated by the following examples. In the materials and computation section, the paper Advanced ensemble modelling of flexible macromolecules using X-ray solution scattering by Tria et

IUCrJ (2015). 2, 475–476 http://dx.doi.org/10.1107/S2052252515015626 475 editorial al. (2015) describes new developments in the methods for other experiments that depend strongly on the coherence studying unstructured and flexible molecules by SAXS. The properties of the beam. These wishes of the scientists are likely biology and medicine section of IUCrJ contains examples of to be fulfilled when the next generation of light sources the use of SAXS in complex biological systems (Tian et al., becomes operational in the near future. In the paper The 2015). potential of future light sources to explore the structure and Synchrotron radiation has contributed immensely to the function of matter by Edgar Weckert (2015), the author development of structural biology. Therefore, it is worth provides the technical background for the performance of the mentioning the paper by Helliwell & Mitchell (2015) in the new light sources that are under construction in Sweden biology and medicine section. The authors provide both an (MAX IV) and Brazil (SIRIUS) in a comparison with the excellent overview of the present state of instrumentation, performance of free electron laser facilities. The paper also automation and data analysis and an outlook on future gives a good overview of the scientific opportunities in terms developments. of new types of experiments that can benefit from the higher The experiments performed with free electron lasers brightness, the smaller emittance and the coherence of the (FELs) on small crystals of proteins have materialized in a beam. The first of the new generation of light sources, MAX new field ‘serial crystallography’ (Chapman et al., 2011). A IV, starts operating in 2016 and one could expect that this will very informative review covering the first five years of this lead to new technical developments and new scientific results field has been written by Ilme Schlichting (2015). Advanced for publication in IUCrJ. instrumentation has been used for the measurement of serial crystallographic data, but handling of the sparse data obtained from the experiment seems to be equally important; Ayyer et al. (2015) show how use of the appropriate algorithm makes it References possible to generate crystallographic intensities from sparse Ayyer, K., Philipp, H. T., Tate, M. W., Wierman, J. L., Elser, V. & data, a result that may have a great impact on the develop- Gruner, S. M. (2015). IUCrJ, 2, 29–34. ment of synchrotron radiation serial crystallography. Bras, W., Koizumi, S. & Terrill, N. J. (2014). IUCrJ, 1, 478–491. X-ray techniques for innovation in industry is the title of a Chapman, H. N., Fromme, P., Barty, A., White, T. A., Kirian, R. A., Aquila, A., Hunter, M. S., Schulz, J., DePonte, D. P., Weierstall, U., feature article in the neutron and synchrotron section Doak, R. B., Maia, F. R. N. C., Martin, A. V., Schlichting, I., Lomb, authored by Lawniczak-Jablonska & Cutler (2014). This paper L., Coppola, N., Shoeman, R. L., Epp, S. W., Hartmann, R., Rolles, is a source of inspiration for increased collaborations/inter- D., Rudenko, A., Foucar, L., Kimmel, N., Weidenspointner, G., actions between companies and researchers at universities and Holl, P., Liang, M., Barthelmess, M., Caleman, C., Boutet, S., research institutions. The experimental set-up at present Bogan, M. J., Krzywinski, J., Bostedt, C., Bajt, S., Gumprecht, L., Rudek, B., Erk, B., Schmidt, C., Ho¨mke, A., Reich, C., Pietschner, synchrotron facilities provides unique opportunities for the D., Stru¨der, L., Hauser, G., Gorke, H., Ullrich, J., Herrmann, S., characterization of all types of materials by a variety of Schaller, G., Schopper, F., Soltau, H., Ku¨hnel, K., Messerschmidt, techniques: spectroscopy, diffraction, imaging and scattering. M., Bozek, J. D., Hau-Riege, S. P., Frank, M., Hampton, C. Y., In the paper the authors describe how the needs of industry Sierra, R. G., Starodub, D., Williams, G. J., Hajdu, J., Timneanu, N., can be met by synchrotron facilities and how this has been Seibert, M. M., Andreasson, J., Rocker, A., Jo¨nsson, O., Svenda, M., Stern, S., Nass, K., Andritschke, R., Schro¨ter, C., Krasniqi, F., Bott, stimulated by a project supported by the European Union. M., Schmidt, K. E., Wang, X., Grotjohann, I., Holton, J. M., The paper illustrates the present level of industrial colla- Barends, T. R. M., Neutze, R., Marchesini, S., Fromme, R., Schorb, borations and the great potential for enhancing them in the S., Rupp, D., Adolph, M., Gorkhover, T., Andersson, I., Hirsemann, future. H., Potdevin, G., Graafsma, H., Nilsson, B. & Spence, J. C. H. The large neutron and X-ray facilities are serving a wide (2011). Nature, 470, 73–77. Helliwell, J. R. & Mitchell, E. P. (2015). IUCrJ, 2, 283–291. range of scientific communities extremely well. Synchrotron Hexemer, A. & Mu¨ller-Buschbaum, P. (2015). IUCrJ, 2, 106–125. radiation has had a tremendous impact on the characterization Lawniczak-Jablonska, K. & Cutler, J. (2014). IUCrJ, 1, 604–613. of all types of materials from hard to biological and has Liang, M., Harder, R. & Robinson, I. K. (2014). IUCrJ, 1, 172–178. contributed to the development of new materials. Scientists in Schlichting, I. (2015). IUCrJ, 2, 245–255. a broad range of fields are familiar with the use of photons Tian, X., Vestergaard, B., Thorolfsson, M., Yang, Z., Rasmussen, H. B. & Langkilde, A. (2015). IUCrJ, 2, 9–18. generated by third generation storage rings. However, there Tria, G., Mertens, H. D. T., Kachala, M. & Svergun, D. I. (2015). are also some experiments that could benefit if the beam of IUCrJ, 2, 207–217. photons had a higher brightness and smaller emittance, and Weckert, E. (2015). IUCrJ, 2, 230–245.

476 Sine Larsen More than crystal structures IUCrJ (2015). 2, 475–476